The subject matter herein relates generally to air purifying respirator masks, and more particularly, to respirator masks that filter inhaled and/or exhaled air.
Masks such as respirator masks may be worn by individuals who wish to protect themselves from toxic airborne contaminants such as particulates, vapors and gases. Particulates may be airborne pathogens, toxins, aerosols, and the like. For example, some known filter masks include filters that remove contaminants from air that is inhaled into the masks. Some known filter masks include one or more filters. The filters may be joined to the mask on either side or both sides of the mouth of the person wearing the mask, directly in front of the mouth, or chest mounted with air routed through a breathing tube to the mask. The filters are generally located in a forward position such that the air that is inhaled into the filters is drawn in from the atmosphere in front of and to the opposite sides of the wearer's face.
Air that is exhaled from the filter masks may be expelled from the front of the masks. For example, some known masks direct the exhaled air out of the front of the mask into the atmosphere in front of the wearer's face. Some known masks include an exhalation filter that filters the exhaled air prior to expelling the exhaled air out of the mask. For example, the exhalation filter may remove aerosols and particulates from the exhaled air. Some known masks include an exhalation duct that produces a tortuous path which reduces the likelihood of contaminants leaking into the mask through the exhalation path. For example, the exhalation duct prevents ambient contaminants from entering the area adjacent to the exhalation valve prior to the valve closing during inhalation. Such a duct may not alter the nature or directions in which air is exhaled from the mask.
Some healthcare workers don air purifying respirators when working with patients who are ill. For example, during a pandemic flu outbreak, doctors, nurses, first responders, and other healthcare providers are advised to wear a respirator when treating patients. Healthcare workers may see multiple patients during a standard working shift, not all of which are infected. The healthcare workers may wear the masks to filter inhaled air in an attempt to avoid contracting the same illness from which the patients are suffering. But, the filters on the masks only serve to concentrate the respirable particles of pathogen on the filter media and non-respirable particles on surfaces directly exposed to droplet spray and contact. Transmission of the pathogen can occur by many routes: contact exposure and subsequent hand to face contact, droplet spray exposure through projection by coughing or sneezing of fluid particles with diameters greater than 100 μm, and airborne (inhalation of respirable particles) exposure. The infectious potential and percentage occurrence of each route is dependent upon the specific pathogen, environmental factors, and nature of the healthcare procedure. Many known filters are difficult to clean without damaging the filter media, therefore requiring change out of the filter prior to its normal end of service life to avoid contact exposure and transmission to non-infected patients and the wearer. This places an extra demand for filters and during a pandemic scenario lead to shortages of filters for masks.
Conversely, the healthcare worker that is wearing the respirator mask may be ill. As a result, the air that is exhaled by the worker may contain pathogens that may be transmitted by one or all three of the routes described earlier. Some known exhalation paths on air purifying respirators direct the exhaled air away and in front of the wearer. The exhaled air may contain droplet spray and respirable particles. The droplet spray can contaminate surfaces immediately in front of the wearer including another person who is interacting with the healthcare worker. The respirable particles can be transported directly into the breathing zone of another person who is interacting with the healthcare worker.
Thus, some known filter masks do not adequately protect both the people who wear the filter masks and the people who are interacting with those wearing the filter masks from some potential routes of transmission. The air being filtered is inhaled from the direction of the potentially infected individual and the filter is not protected from surface contamination due to droplet spray. This burdens the filter with a higher concentration of respirable particles to filter and requires filter change out to avoid infection of the wearer or other individuals due to surface contamination of the filter surface. Similarly, contaminated air may be exhaled by persons wearing the masks and infect those persons who are interacting with the persons wearing the masks. A need exists for a filter mask that better protects the people who wear the mask and the people who interact with the persons wearing the masks from contaminated air.